Anti-tilt and rotation techniques for a touchsurface assembly having translating keys

ABSTRACT

The key assembly comprises a keycap having a touchsurface for receiving a press force that moves the keycap from an unpressed position toward a pressed position. The keycap has first and second ramp contacting features comprising first and second angular protrusions. The first and second angular protrusions have first and second protrusion angles relative to first and second side portions of the keycap (respectively). The key assembly also has a base having first and second ramps that contact the first and second ramp contacting features and guide the keycap in the press direction and the second direction as the keycap moves from the unpressed position toward the pressed position. The base has first and second angular features configured to contact the first and second angular protrusions of the first and second ramp contacting features (respectively) to resist rotation of the keycap as the keycap moves toward the pressed position.

RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No.61/783,316 filed Mar. 14, 2013.

FIELD OF THE INVENTION

This invention generally relates to electronic devices.

BACKGROUND OF THE INVENTION

Pressable touchsurfaces (touch surfaces which can be pressed) are widelyused in a variety of input devices, including as the surfaces of keys orbuttons for keypads or keyboards, and as the surfaces of touch pads ortouch screens. It is desirable to improve the usability of these inputsystems.

FIG. 2 shows a graph 200 of an example tactile response curve associatedwith the “snapover” haptic response found in many keys enabled withmetal snap domes or rubber domes. Specifically, graph 200 relates forceapplied to the user by a touchsurface of the key and the amount of keydisplacement (movement relative to its unpressed position). The forceapplied to the user may be a total force or the portion of the totalforce along a particular direction such as the positive or negativepress direction. Similarly, the amount of key displacement may be atotal amount of key travel or the portion along a particular directionsuch as the positive or negative press direction.

The force curve 210 shows four key press states 212, 214, 216, 218symbolized with depictions of four rubber domes at varying amounts ofkey displacement. The key is in the “unpressed” state 212 when no pressforce is applied to the key and the key is in the unpressed position(i.e., “ready” position). In response to press input, the key initiallyresponds with some key displacement and increasing reaction forceapplied to the user. The reaction force increases with the amount of keydisplacement until it reaches a local maximum “peak force” F₁ in the“peak” state 214. In the peak state 214, the metal snap dome is about tosnap or the rubber dome is about to collapse. The key is in the“contact” state 216 when the keycap, snap dome or rubber dome, or otherkey component moved with the keycap makes initial physical contact withthe base of the key (or a component attached to the base) with the localminimum “contact force” F₂. The key is in the “bottom” state 218 whenthe key has travelled past the “contact” state and is mechanicallybottoming out, such as by compressing the rubber dome in keys enabled byrubber domes.

A snapover response is defined by the shape of the reaction forcecurve—affected by variables such as the rate of change, where it peaksand troughs, and the associated magnitudes. The difference between thepeak force F₁ and the contact force F₂ can be termed the “snap.” The“snap ratio” can be determined as (F₁−F₂)/F₁ (or as 100*(F₁−F₂)/F₁, if apercent-type measure is desired).

BRIEF SUMMARY OF THE INVENTION

Methods and apparatus for a touchsurface assembly such as a key assemblyare described. The key assembly comprises a keycap having a touchsurfacefor receiving a press force that moves the keycap from an unpressedposition toward a pressed position. The unpressed position and pressedposition are separated in a press direction and a second directionorthogonal to the press direction. The keycap has first and second rampcontacting features comprising first and second angular protrusions. Thefirst and second angular protrusions have first and second protrusionangles relative to first and second side portions of the keycap(respectively). The key assembly also comprises a base having first andsecond ramps that contact the first and second ramp contacting featuresand guide the keycap in the press direction and the second direction asthe keycap moves from the unpressed position toward the pressedposition. The base has first and second angular features configured tocontact the first and second angular protrusions of the first and secondramp contacting features (respectively) to resist rotation of the keycapas the keycap moves toward the pressed position.

BRIEF DESCRIPTION OF DRAWINGS

Example embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings which are not toscale unless otherwise noted, where like designations denote likeelements, and:

FIG. 1 shows an example keyboard that incorporates one or moreimplementations of key-based touchsurfaces configured in accordance withthe techniques described herein;

FIG. 2 is a graph of an example tactile response that is characteristicof many keys enabled with metal snap domes or rubber domes;

FIGS. 3A-3B are simplified side views of a first example touchsurfaceassembly configured in accordance with the techniques described herein;

FIG. 4 shows an exploded view of an example keyboard in accordance withthe techniques described herein

FIG. 5A is a top plan view of a touchsurface assembly according to anembodiment;

FIG. 5B is a perspective bottom view of the touchsurface assembly ofaccording to an embodiment;

FIG. 6A is a perspective view of the keycap of FIGS. 5A-B;

FIG. 6B is a perspective view of the bottom surface of the base of FIGS.5A-B;

FIGS. 7A-B show simplified cross-section side views of an exampletouchsurface assembly according to an embodiment; and

FIG. 8 is flow chart illustrating a method of effecting motion of akeycap of a key assembly according to an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention.

Various embodiments of the present invention provide input devices andmethods that facilitate improved usability, thinner devices, easierassembly, lower cost, more flexible industrial design, or a combinationthereof. These input devices and methods involve pressable touchsurfacesthat may be incorporated in any number of devices. As some examples,pressable touchsurfaces may be implemented as surfaces of touchpads,touchscreens, keys, buttons, and the surfaces of any other appropriateinput device. Thus, some non-limiting examples of devices that mayincorporate pressable touchsurfaces include personal computers of allsizes and shapes, such as desktop computers, laptop computers, netbooks,ultrabooks, tablets, e-book readers, personal digital assistants (PDAs),and cellular phones including smart phones. Additional example devicesinclude data input devices (including remote controls, integratedkeyboards or keypads such as those within portable computers, orperipheral keyboards or keypads such as those found in tablet covers orstand-alone keyboards, control panels, and computer mice), and dataoutput devices (including display screens and printers). Other examplesinclude remote terminals, kiosks, point-of-sale devices, video gamemachines (e.g., video game consoles, portable gaming devices, and thelike) and media devices (including recorders, editors, and players suchas televisions, set-top boxes, music players, digital photo frames, anddigital cameras).

The discussion herein focuses largely on rectangular touchsurfaces.However, the touchsurfaces for many embodiments can comprises othershapes. Example shapes include triangles, quadrilaterals, pentagons,polygons with other numbers of sides, shapes similar to polygons withrounded corners or nonlinear sides, shapes with curves, elongated orcircular ellipses circles, combinations shapes with portions of any ofthe above shapes, non-planar shapes with concave or convex features, andany other appropriate shape.

In addition, although the discussion herein focuses largely on thetouchsurfaces as being atop rigid bodies that undergo rigid body motion,some embodiments may comprise touchsurfaces atop pliant bodies thatdeform. “Rigid body motion” is used herein to indicate motion dominatedby translation or rotation of the entire body, where the deformation ofthe body is negligible. Thus, the change in distance between any twogiven points of the touchsurface is much smaller than an associatedamount of translation or rotation of the body.

Also, in various implementations, pressable touchsurfaces may compriseopaque portions that block light passage, translucent or transparentportions that allow light passage, or both.

FIG. 1 shows an example keyboard 100 that incorporates a plurality of(two or more) pressable key-based touchsurfaces configured in accordancewith the techniques described herein. The example keyboard 100 comprisesrows of keys 120 of varying sizes surrounded by a keyboard bezel 130.Keyboard 100 has a QWERTY layout, even though the keys 120 are not thuslabeled in FIG. 1. Other keyboard embodiments may comprise differentphysical key shapes, key sizes, key locations or orientations, ordifferent key layouts such as DVORAK layouts or layouts designed for usewith special applications or non-English languages. In some embodiments,the keys 120 comprise keycaps that are rigid bodies, such as rigidrectangular bodies having greater width and breadth than depth (depthbeing in the Z direction as explained below). Also, other keyboardembodiments may comprise a single pressable key-based touchsurfaceconfigured in accordance with the techniques described herein, such thatthe other keys of these other keyboard embodiments are configured withother techniques.

Orientation terminology is introduced here in connection with FIG. 1,but is generally applicable to the other discussions herein and theother figures unless noted otherwise. This terminology introduction alsoincludes directions associated with an arbitrary Cartesian coordinatesystem. The arrows 110 indicate the positive directions of the Cartesiancoordinate system, but do not indicate an origin for the coordinatesystem. Definition of the origin will not be needed to appreciate thetechnology discussed herein.

The face of keyboard 100 including the exposed touchsurfaces configuredto be pressed by users is referred to as the “top” 102 of the keyboard100 herein. Using the Cartesian coordinate directions indicated by thearrows 110, the top 102 of the keyboard 100 is in the positive-Zdirection relative to the bottom 103 of the keyboard 100. The part ofthe keyboard 100 that is typically closer to the body of a user when thekeyboard 100 is in use atop a table top is referred to as the “front”104 of the keyboard 100. In a QWERTY layout, the front 104 of thekeyboard 100 is closer to the space bar and further from thealphanumeric keys. Using the Cartesian coordinate directions indicatedby the arrows 110, the front 104 of the keyboard 100 is in thepositive-X direction relative to the back 105 of the keyboard 100. In atypical use orientation where the top 102 of the keyboard 100 is facingupwards and the front 104 of the keyboard 100 is facing towards theuser, the “right side” 106 of the keyboard 100 is to the right of auser. Using the Cartesian coordinate directions indicated by the arrows110, the right side 106 of the keyboard 100 is in the positive-Ydirection relative to the “left side” 107 of the keyboard 100. With thetop 102, front 104, and right side 106 thus defined, the “bottom” 103,“back” 105, and “left side” 107 of the keyboard 100 are also defined.

Using this terminology, the press direction for the keyboard 100 is inthe negative-Z direction, or vertically downwards toward the bottom ofthe keyboard 100. The X and Y directions are orthogonal to each otherand to the press direction. Combinations of the X and Y directions candefine an infinite number of additional lateral directions orthogonal tothe press direction. Thus, example lateral directions include the Xdirection (positive and negative), the Y direction (positive andnegative), and combination lateral directions with components in boththe X and Y directions but not the Z direction. Motion components in anyof these lateral directions is sometimes referred herein as “planar,”since such lateral motion components can be considered to be in a planeorthogonal to the press direction.

Some or all of the keys of the keyboard 100 are configured to movebetween respective unpressed and pressed positions that are spaced inthe press direction and in a lateral direction orthogonal to the pressdirection. That is, the touchsurfaces of these keys exhibit motionhaving components in the negative Z-direction and in a lateraldirection. In the examples described herein, the lateral component isusually in the positive X-direction or in the negative X-direction forease of understanding. However, in various embodiments, and withreorientation of select key elements as appropriate, the lateralseparation between the unpressed and the pressed positions may be solelyin the positive or negative X-direction, solely in the positive ornegative Y-direction, or in a combination with components in both the Xand Y directions.

Thus, these keys of the keyboard 100 can be described as exhibiting“diagonal” motion from the unpressed to the pressed position. Thisdiagonal motion is a motion including both a “Z” (or vertical)translation component and a lateral (or planar) translation component.Since this planar translation occurs with the vertical travel of thetouchsurface, it may be called “planar translational responsiveness tovertical travel” of the touchsurface, or “vertical-lateral travel.”

Some embodiments of the keyboard 100 comprise keyboards with leveledkeys that remain, when pressed during normal use, substantially level inorientation through their respective vertical-lateral travels. That is,the keycaps of these leveled keys (and thus the touchsurfaces of thesekeys) exhibit little or no rotation along any axes in response topresses that occur during normal use. Thus, there is little or no roll,pitch, and yaw of the keycap and the associated touchsurfaces remainrelatively level and substantially in the same orientation during theirmotion from the unpressed position to the pressed position.

In various embodiments, the lateral motion associated with thevertical-lateral travel can improve the tactile feel of the key byincreasing the total key travel for a given amount of vertical travel inthe press direction. In various embodiments, the vertical-lateral travelalso enhances tactile feel by imparting to users the perception that thetouchsurface has travelled a larger vertical distance than actuallytravelled. For example, the lateral component of vertical-lateral travelmay apply tangential friction forces to the skin of a finger pad incontact with the touchsurface, and cause deformation of the skin andfinger pad that the user perceives as additional vertical travel. Thisthen creates a tactile illusion of greater vertical travel. In someembodiments, returning the key from the pressed to the unpressedposition on the return stroke also involves simulating greater verticaltravel using lateral motion.

To enable the keys 120 of the keyboard 100 with vertical-lateral travel,the keys 120 are parts of key assemblies each comprising mechanisms foreffecting planar translation, readying the key 120 by holding theassociated keycap in the unpressed position, and returning the key 120to the unpressed position. Some embodiments further comprise mechanismsfor leveling keycaps. Some embodiments achieve these functions with aseparate mechanism for each function, while some embodiments achieve twoor more of these functions using a same mechanism. For example, a“biasing” mechanism may provide the readying function, the returningfunction, or both the readying and returning functions. Mechanisms whichprovide both readying and returning functions are referred to herein as“ready/return” mechanisms. As another example, aleveling/planar-translation-effecting mechanisms may level and effectplanar translation. As further examples, other combinations of functionsmay be provided by a same mechanism.

The keyboard 100 may use any appropriate technology for detectingpresses of the keys of the keyboard 100. For example, the keyboard 100may employ a key switch matrix based on conventional resistive membraneswitch technology. The key switch matrix may be located under the keys120 and configured to generate a signal to indicate a key press when akey 120 is pressed. Alternatively, the example keyboard 100 may employother key press detection technology to detect any changes associatedwith the fine or gross change in position or motion of a key 120.Example key press detection technologies include various capacitive,resistive, inductive, magnetic, force or pressure, linear or angularstrain or displacement, temperature, aural, ultrasonic, optical, andother suitable techniques. With many of these technologies, one or morepreset or variable thresholds may be defined for identifying presses andreleases.

As a specific example, capacitive sensor electrodes may be disposedunder the touchsurfaces, and detect changes in capacitance resultingfrom changes in press states of touchsurfaces. The capacitive sensorelectrodes may utilize “self capacitance” (or “absolute capacitance”)sensing methods based on changes in the capacitive coupling between thesensor electrodes and the touchsurface. In some embodiments, thetouchsurface is conductive in part or in whole, or a conductive elementis attached to the touchsurface, and held at a constant voltage such assystem ground. A change in location of the touchsurface alters theelectric field near the sensor electrodes below the touchsurface, thuschanging the measured capacitive coupling. In one implementation, anabsolute capacitance sensing method operates with a capacitive sensorelectrode underlying a component having the touchsurface, modulates thatsensor electrodes with respect to a reference voltage (e.g., systemground), and detects the capacitive coupling between that sensorelectrode and the component having the touchsurface for gauging thepress state of the touchsurface.

Some capacitive implementations utilize “mutual capacitance” (or“transcapacitance”) sensing methods based on changes in the capacitivecoupling between sensor electrodes. In various embodiments, theproximity of a touchsurface near the sensor electrodes alters theelectric field between the sensor electrodes, thus changing the measuredcapacitive coupling. The touchsurface may be a conductive ornon-conductive, electrically driven or floating, as long as its motioncauses measurable change in the capacitive coupling between sensorelectrodes. In some implementations, a transcapacitive sensing methodoperates by detecting the capacitive coupling between one or moretransmitter sensor electrodes (also “transmitters”) and one or morereceiver sensor electrodes (also “receivers”). Transmitter sensorelectrodes may be modulated relative to a reference voltage (e.g.,system ground) to transmit transmitter signals. Receiver sensorelectrodes may be held substantially constant relative to the referencevoltage to facilitate receipt of resulting signals. A resulting signalmay comprise effect(s) corresponding to one or more transmitter signals,and/or to one or more sources of environmental interference (e.g., otherelectromagnetic signals). Sensor electrodes may be dedicatedtransmitters or receivers, or may be configured to both transmit andreceive.

In one implementation, a trans-capacitance sensing method operates withtwo capacitive sensor electrodes underlying a touchsurface, onetransmitter and one receiver. The resulting signal received by thereceiver is affected by the transmitter signal and the location of thetouchsurface.

In some embodiments, the sensor system used to detect touchsurfacepresses may also detect pre-presses. For example, a capacitive sensorsystem may also be able to detect a user lightly touching atouchsurface, and distinguish that from the press of the touchsurface.Such a system can support multi-stage touchsurface input, which canrespond differently to light touch and press.

Some embodiments are configured to gauge the amount of force beingapplied on the touchsurface from the effect that the force has on thesensor signals. That is, the amount of depression of the touchsurface iscorrelated with one or more particular sensor readings, such that theamount of press force can be determined from the sensor reading(s).

In some embodiments, substrates used for sensing are also used toprovide backlighting associated with the touchsurfaces. As a specificexample, in some embodiments utilizing capacitive sensors underlying thetouchsurface, the capacitive sensor electrodes are disposed on atransparent or translucent circuit substrate such as polyethyleneterephthalate (PET), another polymer, or glass. Some of thoseembodiments use the circuit substrate as part of a light guide systemfor backlighting symbols viewable through the touchsurfaces.

FIG. 1 also shows a section line A-A′ relative to the key 122 of thekeyboard 100, which will be discussed below.

The keyboard 100 may be integrated into or coupled to computer such as alaptop computer comprising one or more processing systems. Theprocessing system(s) each comprise one or more ICs (integrated circuits)having appropriate processor-executable instructions for responding tokey presses. These instructions direct the appropriate IC(s) to operatekeyboard sensors to determine if a key has been pressed (or the extentof the press), and provide an indication of press status to a main CPUof the laptop or a response to the press status to a user of the laptop.

While the orientation terminology, vertical-lateral travel, sensingtechnology, and implementation options discussed here focuses on thekeyboard 100, these discussions are readily analogized to othertouchsurfaces and devices described herein.

Various embodiments in accordance with the techniques described herein,including embodiments without metal snap domes or rubber domes, provideforce response curves similar to the curve 210 of FIG. 2. Many tactilekeyboard keys utilize snap ratios no less than 0.4 and no more than 0.6.Other tactile keyboard keys may use snap ratios outside of these ranges,such as no less than 0.3 and no more than 0.5, and no less than 0.5 andno more than 0.7.

Other embodiments provide other response curves having other shapes,including those with force and key travel relationships that are linearor nonlinear. Example nonlinear relationships include those which arepiecewise linear, which contain linear and nonlinear sections, or whichhave constantly varying slopes. The force response curves may also benon-monotonic, monotonic, or strictly monotonic.

For example, the keys 120 made in accordance with the techniquesdescribed herein may be configured to provide the response shown bycurve 210, or any appropriate response curve. The reaction force appliedto a user may increase linearly or nonlinearly relative to an amount oftotal key travel, an amount of key travel the press direction, or anamount of key travel in a lateral direction. As a specific example, theforce applied may increase with a constant slope relative to the amountof key travel for up to a first amount of force or key movement relativeto its unpressed position, and then plateau (with constant force) ordecrease for up to a second amount of force or key movement.

FIGS. 3A-3B are simplified cross-sectional views of a first exampletouchsurface assembly. The key assembly 300 may be used to implementvarious keys, including the key 122 of the keyboard 100. In theembodiment where FIGS. 3A-3B depict the key 122, these figuresillustrate A-A′ sectional views of the key 122. FIG. 3A shows theexample key assembly 300 in an unpressed position and FIG. 3B shows thesame key assembly 300 in a pressed position. The key assembly 300 mayalso be used in other devices utilizing keys, including keyboards otherthan the keyboard 100 and any other appropriate key-using device.Further, assemblies analogous to the key assembly 300 may be used toenable non-key touchsurface assemblies such as buttons, opaquetouchpads, touchscreens, or any of the touchsurface assemblies describedherein.

The key assembly 300 includes a keycap 310 that is visible to users andconfigured to be pressed by users, a ready/return mechanism 320, and abase 340. The unpressed and pressed positions of the keycap 310 arespaced in a press direction and in a first lateral direction orthogonalto the press direction. The press direction is analogous to the keymotion found in conventional keyboards lacking lateral key motion, is inthe negative-Z direction, and is the primary direction of press and keymotion. In many keyboards the press direction is orthogonal to thetouchsurface of the keycap or the base of the key, such that users wouldconsider the press direction to be downwards toward the base.

The components of the key assembly 300 may be made from any appropriatematerial, including plastics such as polycarbonate (PC), acrylonitrilebutadiene styrene (ABS), nylon, and acetal, metals such as steel andaluminum, elastomers such as rubber, and various other materials. Invarious embodiments, the keycap 310 is configured to be substantiallyrigid, such that the touchsurface of the keycap 310 appears to unaidedhuman senses to move with rigid body motion between its unpressed andpressed positions during normal operation.

The ready/return mechanism 320 is a type of “biasing mechanism” thatprovides both readying and returning functions. The ready/returnmechanism 320 physically biases the keycap 310 during at least part ofthe key press operation. It should be noted that a mechanism which onlyprovides readying or returning function may also be termed a “biasingmechanism,” if it biases the keycap 310 during at least part of the keypress operation. The ready/return mechanism 320 is configured to holdthe keycap 310 in its unpressed position so that the keycap 310 is readyto be pressed by a user. In addition, the ready/return mechanism 320 isalso configured to return the keycap 310 partially or entirely to theunpressed position in response to a release of the press force to keycap310. The release of the press force may be a removal of the press force,or a sufficient reduction of press force such that the key assembly isable to return the keycap 310 to the unpressed position as a matter ofnormal operation. In the example embodiment of FIG. 3, the key assembly300 utilizes magnetically coupled components 322, 324 to form theready/return mechanism 320. Magnetically coupled components 322, 324 mayboth comprise magnets, or one may comprise a magnet while the othercomprise a magnetically coupled material such as a ferrous material.Although magnetically coupled components 322, 324 are each shown as asingle rectangular shape, either or both magnetically coupled components322, 324 may comprise non-rectangular cross-section(s) or comprise aplurality of magnetically coupled subcomponents having the same ordifferent cross sections. For example, magnetically coupled component322 or 324 may comprise a magnetic, box-shaped subcomponent disposedagainst a central portion of a ferrous, U-shaped subcomponent.

In some implementations, the magnetically coupled component 322 isphysically attached to a bezel or base proximate to the keycap 310. Themagnetically coupled component 324 is physically attached to the keycapand magnetically interacts with the magnetically coupled component 322.The physical attachment of the magnetically coupled components 322, 324may be direct or indirect (indirectly being through one or moreintermediate components), and may be accomplished by press fits,adhesives, or any other technique or combination of techniques. Theamount of press force needed on the keycap to overcome the magneticcoupling (e.g., overpower the magnetic attraction or repulsion) can becustomized based upon the size, type, shape, and positions of themagnetically coupling components 322, 324 involved.

The key assembly 300 comprises a planar-translation-effecting (PTE)mechanism 330 configured to impart planar translation to the keycap 310when it moves between the unpressed and pressed positions, such that anonzero component of lateral motion occurs. The PTE mechanism 330 isformed from parts of the keycap 310 and the base 340, and comprises fourramps (two ramps 331, 332 are visible in FIGS. 3A-B) disposed on thebase 340. These four ramps are located such that they are proximate tothe corners of the keycap 310 when the key assembly 300 is assembled. Inthe embodiment shown in FIGS. 3A-B, these four ramps (including ramps331, 332) are simple, sloped planar ramps located at an angle to thebase 340. These four ramps (including ramps 331, 332) are configured tophysically contact corresponding ramp contacting features (two rampcontacting features 311, 312 are visible in FIGS. 3A-B) disposed on theunderside of the keycap 310. The ramp contacting features of the keycap310 may be any appropriate shape, including ramps matched to those ofthe ramps on the base 340.

In response to a press force applied to the touchsurface of the keycap310 downwards along the press direction, the ramps on the base 340(including ramps 331, 332) provide reaction forces. These reactionforces are normal to the ramps and include lateral components that causethe keycap 310 to exhibit lateral motion. The ramps and some retentionor alignment features that mate with other features in the bezel orother appropriate component (not shown) help retain and level the keycap310. That is, they keep the keycap 310 from separating from the rampsand in substantially the same orientation when travelling from theunpressed to the pressed position.

As shown by FIGS. 3A-B, the keycap 310 moves in the press direction(negative Z-direction) in response to a sufficiently large press forceapplied to the top of the keycap 310. As a result, the keycap 310 movesin a lateral direction (in the positive X-direction) and in the pressdirection (in the negative Z-direction) due to the reaction forcesassociated with the ramps. The ramp contacting features (e.g., 311, 312)of the keycap 310 ride on the ramps of the base 340 (e.g., 331, 332) asthe keycap 310 moves from the unpressed to the pressed position. Thismotion of the keycap 310 moves the magnetically coupled components 322,324 relative to each other, and changes their magnetic interactions.

FIG. 3B shows the keycap 310 in the pressed position. For the keyassembly 300, the keycap 310 has moved to the pressed position when itdirectly or indirectly contacts the base 340 or has moved far enough tobe sensed as a key press. FIG. 3A-B do not illustrate the sensor(s) usedto detect the press state of the keycap 310, and such sensor(s) may bebased on any appropriate technology, as discussed above.

When the press force is released, the ready/return mechanism 320 returnsthe keycap 310 to its unpressed position. The attractive forces betweenthe magnetically coupled components 322, 324 pull the keycap 310 back upthe ramps (including the ramps 331, 322), toward the unpressed position.

Many embodiments using magnetic forces utilize permanent magnets.Example permanent magnets include, in order of strongest magneticstrength to the weakest: neodymium iron boron, samarium cobalt, alnico,and ceramic. Neodymium-based magnets are rare earth magnets, and arevery strong magnets made from alloys of rare earth elements. Alternativeimplementations include other rare earth magnets, non-rare earthpermanent magnets, and electromagnets.

Although the key assembly 300 utilizes magnetically coupled componentsto form its ready/return mechanism 320, various other techniques can beused instead or in addition to such magnetic techniques in otherembodiments. In addition, separate mechanisms may be used to accomplishthe readying and returning functions separately. For example, one ormore mechanisms may retain the keycap in its ready position and one ormore other mechanisms may return the keycap to its ready position.Examples of other readying, returning, or ready/return mechanismsinclude buckling elastomeric structures, snapping metallic domes,deflecting plastic or metal springs, stretching elastic bands, bendingcantilever beams, and the like. In addition, in some embodiments, theready/return mechanism push (instead of pull) the keycap 310 to resistkeycap motion to the pressed position or to return it to the unpressedposition. Such embodiments may use magnetic repulsion or any otherappropriate technique imparting push forces.

Many variations of or additions to the components of the key assembly300 are possible. For example, other embodiments may include fewer ormore components. As a specific example, another key assembly mayincorporate any number of additional aesthetic or functional components.Some embodiments include bezels that provide functions such as hidingsome of the key assembly from view, protecting the other components ofthe key assembly, helping to retain or guide the touchsurface of the keyassembly, or some other function.

As another example, other embodiments may comprise different keycaps,readying mechanisms, returning mechanisms, PTE mechanisms, levelingmechanisms, or bases. As a specific example, the keycap 310, the base340, or another component that is not shown may comprise protrusions,depressions, or other features that help guide or retain the keycap 310.As another specific example, some embodiments use non-ramp techniques inplace or (or in addition to) ramps to effect planar translation.Examples other PTE mechanisms include various linkage systems, cams,pegs and slots, bearing surfaces, and other motion alignment features.

As yet another example, although the PTE mechanism 330 is shown in FIGS.3A-B as having ramps disposed on the base 340 and ramp contactingfeatures disposed on the keycap 310, other embodiments may have one ormore ramps disposed on the keycap 310 and ramp contacting featuresdisposed on the base 340. Also, the PTE mechanism 330 is shown in FIGS.3A-B as having ramps 331, 332 with simple, sloped plane ramp profiles.However, in various embodiments, the PTE mechanism 330 may utilize otherprofiles, including those with linear, piecewise linear, or nonlinearsections, those having simple or complex curves or surfaces, or thoseincluding various convex and concave features. Similarly, the rampcontacting features on the keycap 310 may be simple or complex, and maycomprise linear, piecewise linear, or nonlinear sections. As somespecific examples, the ramp contacting features may comprise simpleramps, parts of spheres, sections of cylinders, and the like. Further,the ramp contacting features on the keycap 310 may make point, line, orsurface contact the ramps on the base 340 (including ramps 331, 332).“Ramp profile” is used herein to indicate the contour of the surfaces ofany ramps used for the PTE mechanisms. In some embodiments, a singlekeyboard may employ a plurality of different ramp profiles in order toprovide different tactile responses for different keys.

As a further example, embodiments which level their touchsurfaces mayuse various leveling techniques which use none, part, or all of theassociate PTE mechanism.

FIG. 4 shows an exploded view of an example keyboard construction 400 inaccordance with the techniques described herein. A construction like thekeyboard construction 400 may be used to implement any number ofdifferent keyboards, including keyboard 100. Proceeding from the top tothe bottom of the keyboard, the bezel 420 comprises a plurality ofapertures through which keycaps 410 of various sizes are accessible inthe final assembly. Magnetically coupled components 422, 424 areattached to the keycaps 410 or the base 440, respectively. The base 440comprises a plurality of PTE mechanisms (illustrated as simplerectangles on the base 440) configured to guide the motion of thekeycaps 410. Underneath the base 440 is a key sensor 450, whichcomprises one or more layers of circuitry disposed on one or moresubstrates.

Various details have been simplified for ease of understanding. Forexample, adhesives that may be used to bond components together are notshown. Also, various embodiments may have more or fewer components thanshown in keyboard construction 400, or the components may be in adifferent order. For example, the base and the key sensor 450 may becombined into one component, or swapped in the stack-up order.

FIG. 5A shows a top plan view of a key assembly 500 that may be used toenable the key 122 of the keyboard 100. The key assembly 500 may also beused in other devices utilizing keys, including keyboards other than thekeyboard 100 and any other appropriate key-using device. The keyassembly 500 comprises a keycap 502 having a touch surface 504 that auser may press (i.e., impart a press force on the touch surface) to movethe keycap from an unpressed position to a pressed position. As will bediscussed in more detail below, fundamental embodiments of the keyassembly 500 facilitate the keycap moving in a press direction (i.e., inthe negative Z direction in the example of FIG. 5A) and a directionorthogonal to the press direction (e.g., in the positive X direction,which may be toward the user). This dual direction of movement gives theimpression to the user that the keycap has traveled in the negative Zdirection farther than it actually has. This allows a more compact(thinner) touchsurface assembly to impart to the user the feel of aconventional touchsurface assembly (e.g., a computer keyboard).

As illustrated in FIG. 5A, the keycap 502 has first and second key legs(508 and 508′, respectively), extending outward from the keycap 502. Aswill discussed below, the key legs 508 and 508′ have ramp contactingfeatures (526′ in FIG. 5B) that contact and move along ramps (528 and528′ in FIG. 5B) in the base 506 when moving from the unpressed positionto the pressed position. Each key leg 508 and 508′ has an angularprotrusion 510 and 510′ having a protrusion angle θ (512 and 512′)relative to a first second side portion 514 and 514′ (e.g., the backsideportion in this example) and a second side portion 516 and 516′ (e.g., aleft or right side portion in this example) of the keycap 502. Forkeycaps that are not square or rectangular, the first and second sideportions of the keycap may be angles, arcs or other shapes dependingupon the geometry of the keycap.

As will be discussed in more detail below, the angular protrusions 510and 510′ of the keycap resist rotation of the keycap 502 about the Zaxis as the keycap 502 moves from the unpressed position toward thepressed position by contacting angular features in the base 506.Accordingly, the angular protrusion 510 and 510′ may take any formdesired in any particularly embodiment to facilitate the anti-rotationfeature. In some embodiments, the edges of the angular protrusion 510and 510′ may be substantially straight, while in other embodiments theangular protrusion 510 and 510′ may have curved (e.g., convex orconcave) edges or have a radii of curvature.

In some embodiments, the keycap 502 further comprises third and fourthkey legs (518 and 518′, respectively) extending outward from the keycap502. Each key leg 518 and 518′ also has angular protrusions 520 and 520′having a protrusion angle θ′ (522 and 522′) relative to a first side 524and 524′ portion and a second side portion 516 and 516′ of the keycap502. The key legs 518 and 518′ have ramp contacting features (not shownin FIGS. 5A-B) that contact and move along ramps (530′ in FIG. 5B) inthe base 506 when moving from the unpressed position to the pressedposition.

In some embodiments, the protrusion angels 512, 512′, 522 and 522′ areequal, while in other embodiments the protrusion angels 512 and 512′have one angle and 522 and 522′ have a different angle. In someembodiments, the protrusion angels 512, 512′, 522 and 522′ are acuteangles (θ and θ′) in a range of 45-70 degrees. However, it will beappreciated that in some embodiments, the protrusion angles could beobtuse angles to facilitate the anti-rotation feature for the keycap502.

FIG. 5B is perspective bottom view of the key assembly 500. In thisview, the first and second ramps 528 and 528′ in the base 506 that guidethe ramp contacting features (only 526′ shown in FIG. 5B) of the keycap502 can be seen. In those embodiments that have third and fourth keylegs (518 and 518′ in FIG. 5A), corresponding ramps (only 530′ shown inFIG. 5B) are also provided to facilitate movement of the keycap from theunpressed to the pressed position responsive to the application of apress force.

FIGS. 6A-B are perspective bottom views of the keycap 502 and the base506 of FIG. 5A, respectively, that will facilitate appreciation of thefeatures of the key assembly 500. In FIG. 6A, the first and second rampcontacting features 526 and 526′ that contact and move along first andsecond ramps (528 and 528′ in FIG. 6B) in the base 506 are illustrated.Each of the first and second ramp contacting features 526 and 526′ hasan angular protrusions 510 and 510′ having protrusion angles θ asdiscussed above in connection with FIG. 5A. In those embodiments havingthird and fourth key legs (518 and 518′, respectively), angularprotrusions 520 and 520′ having protrusion angles θ′ and ramp contactingfeatures 532 and 532′ contact and move along ramps (530 and 530′ in FIG.6B) in the base 506 when moving from the unpressed position to thepressed position. As noted above, in some embodiments, the protrusionangels 512, 512′, 522 and 522′ (of FIG. 5A) are equal, while in otherembodiments the protrusion angels 512 and 512′ have one angle and 522and 522′ have a different angle. In some embodiments, the protrusionangels 512, 512′, 522 and 522′ are acute angles (θ and θ′) in a range of45-70 degrees. In some embodiments, the protrusion angles 526 and 526′of the angular protrusions 510 and 510′ demark a chevron shape 534oriented substantially toward the center portion of the keycap 502(i.e., in the positive X direction as shown in FIG. 5A). It will beappreciated, however, that in other embodiments the protrusion angles526 and 526′ of the angular protrusions 510 and 510′ demark a chevronshape oriented in other directions.

In some embodiments, a magnetic ready/return mechanism (320 in FIG. 3)is utilized to bias the keycap 502 toward a ready position (e.g., readyto receive a press force). In such embodiments, the keycap 502 mayinclude a recess 536 to receive a first magnetic component of themagnetic ready/return mechanism. In some embodiments, the first magneticcomponent comprises a magnet, while in some embodiments, the firstmagnetic component comprises a non-magnetized ferrous material.

FIG. 6B illustrates a bottom perspective view of the base 506. In thisview, the first and second ramps 528 and 528′ and the third and fourthramps 530 and 530′ can be seen. The first and second ramps 528 and 528′guide the first and second ramp contacting features (526 and 526′ inFIG. 6A) along the ramps toward the pressed position when thetouchsurface 504 of the keycap 502 receives a press force. Similarly,the third and fourth ramp contacting features (532 and 532′ in FIG. 6A)contact and move along the third and fourth ramps 530 and 530′ in thoseembodiments employing the additional ramp guidance.

In some embodiments, the ramp angle of the first and second ramps 528and 528′ is between 45-70 degrees and in some embodiments comprisesramps having a ramp angle of 57 degrees. In some embodiments, the rampangle of the third and fourth ramps 530 and 530′ is the same as thefirst and second ramps 528 and 528′, while in other embodiments thethird and fourth ramps 539 and 530′ have a different ramp angle than thefirst and second ramps 528 and 528′. In those embodiments where thethird and fourth ramps 530 and 530′ have a different ramp angle than thefirst and second ramps 528 and 528′, the ramp angle of the third andfourth ramps 530 and 530′ is shallower than the ramp angle than thefirst and second ramps 528 and 528′ by approximately 3-10 degrees.

The base 506 also comprises angular features 538 and 538′ that contactthe angular protrusions 510 and 510′ of the keycap 502 to resistrotation of the keycap 502 about the Z axis as the keycap 502 moves fromthe unpressed position toward the pressed position. In those embodimentshave the third and fourth ramps 530 and 530′, angular features 540 and540′ are also provided. In this way, when a keycap 502 is pressed nearone of the corners, the keycap 502 will first settle into all of itsramp guiding surfaces. The ramps guiding surfaces comprise the ramps(528, 528′, 530 and 530′) and angular features (538, 538′, 540 and 540′)of the base 506, and ramp contacting features (526, 526′, 532 and 532′)and angular protrusions on the keycap (510, 510′, 520 and 520′).Collectively, these features help resist rotation of the keycap aboutthe Z axes and resist “wobble” in the X or Y axes as the keycap 502moves from the unpressed position toward the pressed position.

In some embodiments, a magnetic ready/return mechanism (320 in FIG. 3)is utilized to bias the keycap 502 toward a ready position (e.g., readyto receive a press force). In such embodiments, the base 506 may includea recess 542 to receive a second magnetic component of the magneticready/return mechanism. In some embodiments, the second magneticcomponent comprises a magnet, while in embodiments where the firstmagnetic component is a magnet, the second magnetic component comprisesa non-magnetized ferrous material.

Also visible in FIG. 6B is the locations in the base 506 for reverseramps 544 and 544′. As will be discussed in more detail below, thereverse ramps 544 and 544′ contact reverse ramp contacting features ofthe keycap 502 as the keycap moves from the unpressed position towardthe pressed position and provide further advantages as will beappreciated.

FIGS. 7A-B illustrate simple cross-section side views of the keyassembly 500 where like reference numeral designations denote likeelements in FIGS. 5-6. In FIG. 7A, the keycap 502 is shown in theunpressed (i.e., ready) position, while in FIG. 7B, the keycap 502 isshown in the pressed position responsive to the touchsurface 504receiving a press force 546.

As noted above, in some embodiments, the ramp angle 548 (φ) of the firstramp 528 is between 45-70 degrees and in some embodiments comprise rampshaving a ramp angle 548 of 57 degrees. In those embodiments implementingthe third and fourth ramps (only the third ramp 530 is shown in FIGS.7A-B), the ramp angle 550 (φ′) of the ramp 530 may be the same as thefirst ramp angle 548, while in other embodiments the third ramp angle550 is a different angle than the first ramp 528. In those embodimentswhere the third ramp 530 has a different ramp angle than the first ramp528, the ramp angle 550 of the third ramp 530 is shallower than the rampangle 548 of the first ramp 528 and by approximately 3-10 degrees. As anon-limiting example, if the ramp angle 548 of the first ramp 528 is 57degrees, then the ramp angle 550 of the third ramp 530 may be 52degrees.

Those embodiments having a shallower third ramp angle 550 as compared tothe first ramp angle 548 offer an advantage in the event a user pressesthe keycap 502 off-center. As a non-limiting example, if the keycap 502were to be pressed near a front edge of the keycap (the left side of thekeycap illustrated in FIG. 7A), the ramp contacting feature 526 may moveaway from the first ramp 528 and thus “float” on the backside of thekeycap because the magnetic ready/return mechanism tends to pull(magnetically attract) the rear of the keycap upward. This can cause thekeycap 502 to tilt and/or about the Y axis while moving toward thepressed position which may result in an undesirable user experience.Additionally, “floating” effect of the keycap may result in inconsistentpositing of the magnetic component of the keycap resulting in erroneoussensing that the keycap has been pressed by the user toward the pressedposition. By having the third ramp angle 550 shallower than the firstramp angle 548, any tilting of the keycap 502 can be reduced. Thisreduction results from the shallower slope of the third ramp 530 drivingthe front of the keycap 502 laterally (i.e., in the positive Xdirection) at a higher rate and the steeper slope of the first ramp 528driving the back of the keycap laterally at a lower rate. The unequalamounts of driven motion compensates for a gap 554 that separates thekey leg 508 and the reverse ramp 544. Typically, the gap 554 is used toease manufacturing tolerance requirements to facilitatemanufacturability of the key assembly 500. Since, the additionalX-direction motion of the third key leg 518 will cause the first key leg508 to contact the reverse ramp 544, the first key leg 508 is providedwith a reverse ramp contacting feature 552, that guides the first keyleg 508 toward the press position (as shown in FIG. 7B) in the eventthat the ramp contacting feature 526 is pulled of the first ramp 528 bythe off-center key press by the user. Additionally, upon removal of thepress force 546, the reverse ramp 544 guides the keycap 502 in thenegative X direction so that the ramp contacting feature 526 can contactthe first ramp 528 as the keycap 502 moves toward the unpressedposition.

In some embodiments, the key assembly 500 includes a sensor 560 fordetecting the pressed state of the keycap 502 or the movement of thekeycap 502 away from the unpressed state. The sensor 560 may use anyappropriate technology, including any of the ones described herein. Insome embodiments, the sensor 560 detects changes in capacitance, thekeycap 502 comprises primarily dielectric material, and the change inthe position of the dielectric material of the keycap 502 causes theprimary changes in capacitance detected by the sensor 560. In someembodiments, the sensor 560 detect changes in capacitance, conductivematerial is disposed in or on the keycap 502, and the change in positionof the conductive material of the keycap 502 causes the primary changesin capacitance detected by the sensor 560. In some embodiments, thesensor 560 is configured to actively detect unpressed and pressedpositions of the keycap 502. In some embodiments, the sensor 560 isconfigured to actively detect only the pressed state of the keycap 502,and it is assumed that no detection of the pressed state means thekeycap 502 is unpressed, or vice versa. A processing system (not shown)communicatively coupled to the sensor 560 operates the sensor 560 toproduce signals indicative of the pressed state of the key assembly, anddetermines a press state of the keycap 502 based on these signals.

FIG. 8 shows an example method 800 that can be used for effecting motionof a pressable touchsurface of a touchsurface assembly, such as, in someembodiments, the keycap of a key assembly. The keycap is configured tomove between an unpressed position and a pressed position relative to abase of the key assembly, where the unpressed and pressed positions areseparated in a press direction and in a lateral direction orthogonal tothe press direction.

In step 802, in response to a press input to the keycap, guiding thekeycap toward the pressed position via ramp contacting features havingangular projections that contact with ramps and angular features in thebase to resist rotation of the keycap as the keycap moves toward thepressed position.

In step 804, in response to a release of the press input, guiding thekeycap toward the unpressed position via magnetic forces of aready-return mechanism.

Thus, the techniques described herein can be used to implement anynumber of devices utilizing different touchsurface assemblies, includinga variety of keyboards each comprising one or more key assemblies inaccordance with the techniques described herein. For example, someembodiments of keyboards, the keys of the keyboard may have angularprotrusions of different shapes or different protrusion angles. In someembodiments, the ramp angles may vary between keys to provide adifferent user experience as the key moves between an unpressed positionand a pressed position.

The implementations described herein are meant as examples, and manyvariations are possible. As one example, any appropriate featuredescribed with one implementation may be incorporated with another. As afirst specific example, any of the implementations described herein mayor may not utilize a finishing tactile, aesthetic, or protective layer.

In addition, the structure providing any function may comprise anynumber of appropriate components. For example, a same component mayprovide leveling, planar translation effecting, readying, and returningfunctions for a key press. As another example, different components maybe provide these functions, such that a first component levels, a secondcomponent effects planar translation, a third component readies, and afourth component returns. As yet another example, two or more componentsmay provide a same function. For example, in some embodiments, magnetsand springs together provide the return function, or the ready andreturn functions.

What is claimed is:
 1. A key assembly, comprising: a keycap having atouch surface for receiving a press force that moves the keycap from anunpressed position toward a pressed position, the unpressed position andpressed position separated in a press direction and a second directionorthogonal to the press direction, the keycap having first and secondramp contacting features comprising first and second angular protrusionshaving first and second protrusion angles relative to first and secondside portions of the keycap, respectively, wherein the first angularprotrusion and the second angular protrusion extend in a plane parallelto a plane of the touch surface, and wherein the first protrusion angleof the first angular protrusion and the second protrusion angle of thesecond angular protrusion are each angled in a direction incident withthe first side portion of the keycap; and a base having first and secondramps that contact the first and second ramp contacting features andguide the keycap in the press direction and the second direction as thekeycap moves from the unpressed position toward the pressed position,the base also having first and second angular features configured tocontact the first and second angular protrusions of the first and secondramp contacting features, respectively; wherein the first and secondangular protrusions contact the first and second angular features toresist rotation of the keycap as the keycap moves toward the pressedposition.
 2. The key assembly of claim 1, wherein: the keycap includes afirst magnetic component; and wherein the base includes a secondmagnetic component; and wherein the first and second magnetic componentsform a ready-return mechanism that biases the keycap toward theunpressed position.
 3. The key assembly of claim 2, wherein at least oneof the first and second magnetic components comprises a non-magnetizedferrous material.
 4. The key assembly of claim 1, wherein the ramps inthe base include reverse ramps and the ramp contacting features includereverse ramp contacting surfaces.
 5. The key assembly of claim 1,wherein: the keycap further comprises third and fourth ramp contactingfeatures extending from the keycap and disposed farther from aready-return mechanism than the first and second ramp contactingfeatures, the third and fourth ramp contacting features comprising thirdand fourth angular protrusions having third and fourth protrusion anglesrelative to first and second side portions of the keycap, respectively;and wherein the base further comprises third and fourth ramps thatcontact the third and fourth ramp contacting features and guide thekeycap in the press direction and the second direction as the keycapmoves from the unpressed position toward the pressed position, the basealso having third and fourth angular features configured to receive thethird and fourth angular protrusions of the third and fourth rampcontacting features, respectively; and wherein the third and fourthangular protrusions contact with the third and fourth angular featuresresist rotation of the keycap as the keycap moves toward the pressedposition.
 6. The key assembly of claim 5, wherein a slope of the firstramp and a slope of the third ramp are different.
 7. The key assembly ofclaim 6, wherein the slope of the third ramp is shallower than the slopeof the first ramp.
 8. The key assembly of claim 6, wherein the slope ofthe third ramp is shallower than the slope of the first ramp by 3-10degrees.
 9. The key assembly of claim 1, wherein the first and secondprotrusion angles of the first and second angular protrusions are acuteangles.
 10. The key assembly of claim 9, wherein the first and secondprotrusion angles of the first and second ramp angular protrusions areeach in a range of 45-70 degrees.
 11. The key assembly of claim 1,wherein the first and second angular protrusions demark a chevron shapeoriented substantially toward a center portion of the keycap.
 12. Thekey assembly of claim 1, further comprising a capacitive sensor forsensing when the keycap is in the pressed position.
 13. A keyboard,comprising: a plurality of keycaps, each keycap of the plurality ofkeycaps having a touch surface for receiving a press force that movesthe keycap from a unpressed position toward a pressed position, theunpressed position and pressed position separated in a press directionand a second direction orthogonal to the press direction; each keycap ofthe plurality of keycaps also having ramp contacting features comprisingfirst and second angular protrusions having first and second protrusionangles relative to first and second side portions of the keycap,respectively, wherein the first angular protrusion and the secondangular protrusion extend in a plane parallel to a plane of the touchsurface, and wherein the first protrusion angle of the angularprotrusion and the second protrusion angle of the second angularprotrusion are each angled in a direction incident with the first sideportion of the keycap; and a base having, for each corresponding keycapof the plurality of keycaps, first and second ramps that contact theramp contacting features of the corresponding keycap, and guide thecorresponding keycap in the press direction and the second direction asthe corresponding keycap moves from the impressed position toward thepressed position, the base also having, for each corresponding keycap ofthe plurality of keycaps, first and second angular features configuredto contact the first and second angular protrusions of the rampcontacting features of the corresponding keycap, respectively, to resistrotation of the corresponding keycap as the corresponding keycap movestoward the pressed position.
 14. The keyboard of claim 13, wherein, foreach keycap of the plurality of the keycaps: the keycap includes a firstmagnetic component; the base includes a second magnetic component; andthe first and second magnetic components form a ready-return mechanismthat biases the keycap towards the unpressed position.
 15. The keyboardof claim 14, wherein, for each keycap of the plurality of keycaps: thekeycap includes third and fourth ramp contacting features extending fromthe keycap and disposed farther from the ready-return mechanism than thefirst and second ramp contacting features of the keycap, the third andfourth ramp contacting features comprising third and fourth angularprotrusions having third and fourth protrusion angles relative to firstand second side portions of the keycap, respectively; and wherein thebase includes third and fourth ramps that contact the third and fourthramp contacting features and guide the keycap in the press direction andthe second direction as the keycap moves from the unpressed positiontoward the pressed position, the base including third and fourth angularfeatures configured to contact the third and fourth angular protrusions,respectively, to resist rotation of the keycap as the press force movesthe keycap toward the pressed position.
 16. The keyboard of claim 15,wherein for a keycap of the plurality of keycaps, a slope of the thirdramp is shallower than a slope of the first ramp.
 17. The keyboard ofclaim 15, wherein the first and second protrusion angles of a keycap ofthe plurality of keycaps are each in a range of 45-70 degrees.
 18. Thekeyboard of claim 13, further comprising capacitive sensor electrodesfor sensing when keycaps of the plurality of keycaps are in the pressedposition.
 19. A method of effecting motion of a keycap of a keyassembly, wherein the keycap is configured to move between an unpressedposition and a pressed position relative to a base, wherein theunpressed and pressed positions are separated in a press direction andin a lateral direction orthogonal to the press direction, the methodcomprising: in response to a press input to the keycap, guiding thekeycap toward the pressed position via ramp contacting features havingangular projections that contact with ramps and angular features in thebase to resist rotation of the keycap as the keycap moves toward thepressed position, wherein the angular projections extend in a planeparallel to a plane of a touch surface of the keycap, and whereinprojection angle of the angular projections is angled in a directionincident with a side portion of the keycap.
 20. The method of claim 19,further comprising: in response to a release of the press input, guidingthe keycap toward the unpressed position via magnetic forces of aready-return mechanism.